1. Field of the Disclosure
The present disclosure relates to a coordinate detecting device that two-dimensionally detects the approach position of a detection target from a change in electrostatic capacitance.
2. Description of the Related Art
As a coordinate detecting device that two-dimensionally detects the approach position of a detection target, a device has been proposed which detects a change in the electrostatic capacitance formed at the intersection point between detection electrodes arranged in a matrix (for example, see Japanese Unexamined Patent Application Publication No. 3-289715). This type of coordinate detecting device includes first electrodes which are arranged in a first axial direction and second electrodes which are arranged in a second axial direction intersecting the first electrodes and are insulated from the first electrodes, and detects a change in capacitance at the intersection points which is determined by combinations of the first electrodes and the second electrodes, thereby specifying the approach position of the detection target.
The coordinate detecting device detects a change in capacitance at all of the intersection points determined by the combinations of the first electrodes and the second electrodes in order to specify the approach position of the detection target. Therefore, it is easy to improve detection sensitivity or resolution. Even when the detection targets approach a plurality of coordinates, it is possible to accurately obtain information about a plurality of approach points.
However, since the coordinate detecting device detects a change in capacitance for all of the combinations of the first electrodes and the second electrodes, the coordinate detecting device including, for example, m first electrodes and n second electrodes needs to measure capacitance m×n times in one coordinate specifying operation. Therefore, when the number of electrodes increases in order to improve the resolution of the coordinate detecting device, the time required to specify the coordinates increases. On the other hand, a plurality of detecting circuits can be used to measure capacitance at a plurality of intersection points in parallel, thereby reducing the time required to specify the coordinates. However, in this case, the size of the circuit increases, which results in an increase in the manufacturing costs of the coordinate detecting device. When the size of the detecting circuit increases, the power consumption of the coordinate detecting device increases proportionately.